Coherent Fiber Optic Breakout Cable Assembly and Method for Fabricating Same

This application claims the benefit of priority of U.S. Provisional Application Ser. No. 63/713,837 filed on Oct. 30, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.

This disclosure relates generally to optical fibers, and more particularly to coherent fiber optic cable breakout assemblies for two-dimensional arrays of optical fibers, and methods for fabricating such fiber optic cable breakout assemblies.

Optical fibers are useful in a wide variety of applications, including the telecommunications industry for voice, video, and data transmission. An exemplary coated optical includes a glass core, glass cladding surrounding the glass core, and a polymer coating (optionally including multiple coating layers) surrounding the glass cladding. An outer diameter of a coated optical fiber may be about 200 μm, about 250 μm, or any other suitable value, while a core diameter of a single-mode optical fiber may be on the order of 8 μm to 10 μm, and a core diameter of a multi-mode optical fiber may be somewhat larger. An additional covering, which may be embodied in a tight buffer layer or a loose tube (also known as a furcation tube or fanout tube), may be applied to one or more coated optical fibers to provide additional protection and allow for easier handling.

In a telecommunications system that uses optical fibers, there are typically many locations where fiber optic cables that carry the optical fibers connect to equipment or other fiber optic cables. To conveniently provide these connections, optical connectors are often provided on the ends of fiber optic cables. Many different types of optical connectors exist, including multi-fiber optical connectors. One example is the multi-fiber push on (MPO) connector having up to 24 optical fibers (e.g., received in two rows of twelve micro-holes defined in a ferrule), with a MPO connector incorporating a mechanical transfer (MT) ferrule being standardized according to TOA-604-5 and IEC 61754-7.

The rapid advances of generative artificial intelligence (AI) in recent years continues to push the size of training models, which double in size roughly every 4 months and require ever-increasing amounts of computing power. Faster graphic processing units (GPUs) and larger GPU clusters are required for high performance computing including generative AI, and the networks connecting GPUs need to support unprecedented bandwidth growth.

Existing pluggable optical transceivers and co-packaged optics for Ethernet networks entail high power consumption on-par with direct attach copper cable (DAC), which is about 5 pJ/bit. Highly parallel optical interconnects using VCCSEL or micro-LED array transceivers operating at lower speeds of about 25 Gb/s per channel have demonstrated much lower power consumption of 1 pJ/bit. Such interconnects require more optical fibers for the same total capacity as compared Ethernet optics, which currently operate at about 100 Gbps or 200 Gbps per lane. Furthermore, optical fibers connecting transmitter arrays to receiver arrays do not require breakouts. It would be highly desirable for fiber bundles to keep the relative positions on both ends so that each transmitter in a transmitter array is connected to a known element in a receiver array. Fiber bundles that are ordered in this respect are referred to as “coherent,” with a one-to-one correspondence concerning the arrangement of input and output fibers.

As optics become tightly integrated with electronic integrated circuits to decrease power consumption, higher bandwidth density is required for optical interconnects. Moving from point-to-point interconnects to point-to-multi-point interconnects can improve density and also consolidate cables.

Making coherent bundle cables with breakouts is more challenging than making conventional trunk cables, in which optical fibers are colored and grouped into ribbons or subunits. Fiber bundle cables rely solely on coherence for fiber identification in order to be cost effective. A fiber bundle typically includes hundreds or even thousands of fibers. To manually separate optical fibers of a trunk fiber bundle one-by-one into many breakout bundles while maintaining coherence would be slow and impractical process. Although it is conceivable to mount groupings of optical fibers in precision mechanical faceplates to form breakout bundles, the presence of internal support structures (i.e., faceplates) for each subunit would inevitably reduce bandwidth density.

Need exists in the art for improved coherent fiber optic cable breakout assemblies for two-dimensional arrays of optical fibers, and methods for fabricating such assemblies, that address limitations associated with conventional assemblies and fabrication methods.

The present disclosure includes coherent fiber optic bundle breakout cable assemblies each comprising a trunk fiber bundle having a plurality of optical fibers in a close-packed 2D array at a trunk connector end face, and multiple breakout bundles emanating from the trunk fiber bundle and each including a group of optical fibers in a close-packed 2D array at a breakout connector end face. In the trunk fiber bundle and each breakout bundle, optical fibers are in lateral contact with one another (e.g., along glass cladding surfaces, or along surface of hard precision coating materials). Bonding material is arranged in interstitial spaces of optical fibers near ends of each breakout bundle. For each breakout bundle, optical fibers at a breakout connector end face are mapped to a set, or a pair of subsets, of optical fibers of the trunk fiber bundle that are contiguous at the trunk connector end face. A method for fabricating such an assembly includes holding the plurality of optical fibers within an elastomeric fixture, dicing the plurality of fibers to provide diced ends thereof, selectively applying and curing bonding material in interstitial spaces between optical fibers proximate to the diced ends according to a bundle-forming pattern, separating groups of optical fibers into breakout bundles, and retaining each breakout bundle in a corresponding breakout bundle ferrule aperture of one or more breakout bundle ferrules.

One aspect of the disclosure relates to a coherent fiber optic bundle breakout cable assembly that comprises a trunk fiber bundle comprising a plurality of optical fibers in a close-packed two-dimensional array configuration at a trunk connector end face, wherein each optical fiber of the plurality of optical fibers is arranged in lateral contact with multiple other optical fibers of the plurality of optical fibers at the trunk connector end face. The coherent fiber optic bundle breakout cable assembly further comprises a plurality of breakout bundles emanating from the trunk fiber bundle, wherein each breakout bundle of the plurality of breakout bundles comprises a group of optical fibers in a close-packed two-dimensional array configuration at a breakout connector end face, and within each breakout bundle, each optical fiber of the group of optical fibers is arranged in lateral contact with multiple other optical fibers of the group of optical fibers at a breakout connector end face. For each breakout bundle of the plurality of breakout bundles, each optical fiber of the group of optical fibers comprises an end along the breakout connector end face, with bonding material arranged in interstitial spaces between at least some optical fibers of the group of optical fibers proximate to the breakout connector end face. Additionally, for each breakout bundle of the plurality of breakout bundles, the optical fibers at the breakout connector end face are mapped to a subset, or pair of subsets, of optical fibers of the trunk fiber bundle that are contiguous at the trunk connector end face.

In certain embodiments, the trunk fiber bundle comprises a trunk marker fiber along a perimeter of the trunk fiber bundle, with the trunk marker fiber comprising a marked coating at least at a location proximate to the trunk connector end face, and with the trunk marker fiber being omitted from the plurality of breakout bundles.

In certain embodiments, each breakout bundle of the plurality of breakout bundles comprises a breakout bundle marker optical fiber comprising a marked coating at least at a location proximate to the breakout connector end face, with the breakout bundle marker optical fiber being indicative of breakout bundle polarity.

In certain embodiments, for each breakout bundle of the plurality of breakout bundles, the group of optical fibers is arranged in a hexagonal close-packed configuration or a rectangular close-packed configuration.

In certain embodiments, the plurality of optical fibers of the trunk fiber bundle is arranged in a hexagonal close-packed configuration or a rectangular close-packed configuration

In certain embodiments, wherein optical fibers of the plurality of optical fibers are bare optical fibers and comprise glass cladding surfaces in lateral contact with one another.

In certain embodiments, each optical fiber of the plurality of optical fibers comprises a core, a cladding layer, and a hard coating layer having a Young's modulus greater than 100 MPa, and optical fibers of the plurality of optical fibers comprise hard coating layer surfaces in lateral contact with one another.

In certain embodiments, each optical fiber of the plurality of optical fibers comprises an outer diameter in a range of 50 μm to 150 μm, or 100 μm to 150 μm.

In certain embodiments, a coherent fiber optic bundle breakout cable assembly includes a trunk fiber bundle ferrule comprising a single bundle ferrule or a multi-bundle ferrule, and defining at least one trunk fiber ferrule aperture receiving the plurality of optical fibers proximate to the trunk connector end face, and the assembly further includes one or more breakout bundle ferrules, each comprising a single bundle ferrule or a multi-bundle ferrule, wherein each breakout bundle ferrule defines at least one breakout bundle aperture receiving a corresponding group of optical fibers of the plurality of breakout bundles.

In certain embodiments, the plurality of optical fibers of the trunk bundle has an optical fiber count in a range of from 60 to 3,000, and for each breakout bundle, the group of optical fibers has an optical fiber count in a range of from 7 to 1,000.

In certain embodiments, adhesive material is provided to bind optical fibers of the plurality of optical fibers at a furcation section embodying a transition from the trunk fiber bundle to the plurality of breakout bundles.

In certain embodiments, cable jacket material is arranged over the trunk fiber bundle and over each breakout bundle of the plurality of breakout bundles

In certain embodiments, a number of optical fibers in the trunk fiber bundle exceeds an aggregate number of optical fibers in the plurality of breakout bundles, with the number of optical fibers in the trunk bundle including one or more non-functional fibers not arranged to transmit optical signals to any breakout bundles of the plurality of breakout bundles.

In certain embodiments, at least one breakout bundle of the plurality of breakout bundles comprises a pair of subgroups of optical fibers of the plurality of optical fibers, with each subgroup of the pair of subgroups of optical fibers in the breakout bundle being mapped to a corresponding subset of the pair of subsets of optical fibers that is contiguous at the trunk connector end face, wherein each subset of the pair of subsets of optical fibers is not in contact with the other subset of the pair of subsets of optical fibers at the trunk connector end face.

Another aspect of the disclosure relates to a method for fabricating a coherent fiber optic bundle breakout cable assembly, the method comprising multiple steps. One step includes terminating a plurality of optical fibers in a close-packed two-dimensional array configuration within a trunk fiber ferrule aperture of a trunk fiber ferrule arranged at a first end portion of the plurality of optical fibers, wherein each optical fiber of the plurality of optical fibers within the trunk fiber ferrule aperture is arranged in lateral contact with multiple other optical fibers of the plurality of optical fibers. Another step includes holding a second length portion of the plurality of optical fibers with an elastomeric fixture, wherein each optical fiber of the plurality of optical fibers within the trunk fiber ferrule aperture is arranged in lateral contact with multiple other optical fibers of the plurality of optical fibers within the elastomeric fixture. Another step includes dicing the plurality of optical fibers proximate to the elastomeric fixture to provide diced ends of optical fibers of the plurality of optical fibers. Another step includes selectively applying bonding material in interstitial spaces between optical fibers of the plurality of optical fibers proximate to the diced ends according to a bundle-forming pattern. Another step includes curing the bonding material selectively applied to the interstitial spaces. Another step includes separating groups of optical fibers of the plurality of optical fibers into a plurality of breakout bundles, wherein each breakout bundle includes a single bundle or a pair of sub-bundles of bonded optical fibers arranged in a close-packed two-dimensional array configuration and generated by curing the bonding material selectively applied to the interstitial spaces. Yet another step includes, for each breakout bundle of the plurality of breakout bundles, retaining the breakout bundle in a corresponding breakout bundle ferrule aperture of one or more breakout bundle ferrules.

In certain embodiments, the method further comprises, for each breakout bundle of the plurality of breakout bundles, inserting a furcation tube over at least a portion of the breakout bundle.

In certain embodiments, the method further comprises terminating each breakout bundle to a pre-defined leg length.

In certain embodiments, the one or more breakout bundle ferrules comprise portions of one or more breakout bundle connectors.

In certain embodiments, the method further comprises immersing the plurality of optical fibers proximate to the elastomeric fixture in an index-matching liquid, wherein the dicing of the plurality of optical fibers comprises laser dicing of the immersed plurality of optical fibers proximate to the elastomeric fixture.

In certain embodiments, the method further comprises applying a mask over the diced ends of optical fibers of the plurality of optical fibers, wherein the selective applying of bonding material in interstitial spaces between optical fibers of the plurality of optical fibers proximate to the diced ends comprises applying bonding material through openings in the mask to produce the bundle-forming pattern of bonding material.

In certain embodiments, the selective applying of bonding material in interstitial spaces between optical fibers of the plurality of optical fibers proximate to the diced ends comprises piezoelectric jetted (e.g., inkjet-style) printing of bonding material in the interstitial spaces to produce the bundle-forming pattern of bonding material.

In certain embodiments, the bonding material comprises UV-curable adhesive material, and the curing of the bonding material selectively applied to the interstitial spaces comprises impinging UV emissions on the bonding material.

In certain embodiments, the trunk fiber bundle comprises a trunk marker fiber along a perimeter of the trunk fiber bundle, with the trunk marker fiber comprising a marked coating at least at a location proximate to the trunk fiber ferrule, and with the trunk marker fiber being omitted from the plurality of breakout bundles.

In certain embodiments, each breakout bundle of the plurality of breakout bundles comprises a breakout bundle marker optical fiber comprising a marked coating at least at a location proximate to the breakout connector end face, with the breakout bundle marker optical fiber being indicative of breakout bundle polarity.

In certain embodiments, the plurality of optical fibers of the trunk fiber bundle is arranged in a hexagonal close-packed configuration or a rectangular close-packed configuration, and for each breakout bundle of the plurality of breakout bundles, the group of optical fibers is arranged in a hexagonal close-packed configuration or a rectangular close-packed configuration.

In another aspect, any two or more features described in connection with the foregoing aspects and/or other embodiments disclosed herein may be combined for additional advantage.

Additional features and advantages will be set out in the detailed description that follows, and in part will be readily apparent to those skilled in the technical field of optical connectivity. It is to be understood that the foregoing general description, the following detailed description, and the accompanying drawings are merely exemplary and intended to provide an overview or framework to understand the nature and character of the claims.

Various embodiments will be further clarified by examples in the description below. In general, the description relates to coherent fiber optic bundle breakout cable assemblies each comprising a trunk fiber bundle having a plurality of optical fibers in a close-packed 2D array at a trunk connector end face, and multiple breakout bundles emanating from the trunk fiber bundle and each including a group of optical fibers in a close-packed 2D array at a breakout connector end face. In the trunk fiber bundle and each breakout bundle, optical fibers are in lateral contact with one another (e.g., along glass cladding surfaces, or along surface of hard precision coating materials). Bonding material is arranged in interstitial spaces of optical fibers near ends of each breakout bundle. For each breakout bundle, optical fibers at a breakout connector end face are mapped to a set, or a pair of subsets, of optical fibers of the trunk fiber bundle that are contiguous at the trunk connector end face. Such mapping provides one-to-one correspondence concerning the arrangement of input and output fibers, without requiring marking of every fiber of a trunk fiber array.

Glass fibers typically have precise cladding-to-core concentricity and precise outer dimensions (i.e., along outer cladding surfaces). However, concerns such as mechanical abrasion, binding, and/or fracturing have limited the practical use and potential reliability of cable assemblies having glass surfaces of optical fibers in direct lateral contact in a packed array. One way to mitigate these concerns is by forming a titanium-doped stress layer portion of (i.e., within) fiber cladding. Another way to mitigate these concerns is by providing a thin, hard, and geometrically precise coating of one or more layers over glass cladding of optical fibers to be arranged in lateral contact with one another. Examples of suitable coating materials include hard polymers, metals, and inorganic materials. Providing a precision hard coating permits exterior surfaces of optical fibers to be arranged in a close-packed array with tight dimensional tolerances, without requiring use of precision mechanical faceplates (that would reduce bandwidth density) or other alignment features, while still providing repeatable fiber alignment at connector ends of a cable assembly. Embodiments here employ optical fibers (whether bare optical fibers or hard coated optical fibers) with outer surfaces in direct lateral contact with other optical fibers in close-packed two-dimensional array configuration within a trunk fiber bundle, and within multiple breakout bundles, of a coherent fiber optic bundle breakout cable assembly. The precise outer dimensions and concentricity of these optical fibers permits the optical fibers themselves to be used as datum surfaces for fiber alignment.

Further details regarding the subject matter of the disclosure are provided hereinafter, after introduction to terminology used in the application.

The use herein of ordinals in conjunction with an element is solely for distinguishing what might otherwise be similar or identical labels, such as “first” and “second,” and does not imply a priority, a type, an importance, or other attribute, unless otherwise stated herein.

The term “about” as used herein in conjunction with a numeric value means any value that is within a range of ten percent greater than or ten percent less than the numeric value.

The term “substantially” used herein in conjunction with a geometric property or characteristic (e.g., “substantially flush”) includes slight deviations from the geometric property/characteristic in question due to manufacturing limitations and tolerances.

In this disclosure, when numerical ranges are discussed (e.g., “X to Y” or “between X and Y”, with X and Y being integers), the ranges include the stated end points.

As used herein, the articles “a” and “an” in reference to an element refers to “one or more” of the element unless otherwise explicitly specified. The word “or” as used herein is inclusive unless contextually impossible. As an example, the recitation of A or B means A, or B, or both A and B.

It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

In this disclosure, the term “optical fiber” (or “fiber”) is used in a generic sense and may encompass bare optical fibers, hard-coated optical fibers, soft-coated optical fibers, or buffered optical fibers, as well as optical fibers including different sections corresponding to these fiber types, unless it is clear from the context which of the types is intended. An “optical fiber” refers to a waveguide having a glass portion optionally surrounded by a coating. The glass portion includes a core and a cladding and is referred to herein as a “glass fiber.” “Bare optical fibers” (including “bare glass optical fibers”) or “bare sections” are those with no coating present on the fiber cladding. A bare optical fiber may have an outer diameter in a range of 50 μm to 150 μm, or 50 μm to 150 μm, in certain embodiments. “Coated optical fibers” or “coated sections” include a single or multi-layer coating material surrounding the fiber cladding. “Hard-coated optical fibers” have a thin (e.g., typically less than 10 μm, such as within a thickness range between 0.1 μm and 10 μm) coating over fiber cladding, with such hard coating typically having a Shore D hardness of greater than 60, or greater than 100, and such hard coating may include a suitable metal, inorganic, and/or hard polymer material. A hard-coated optical fiber may have an outer diameter in a range of 50 μm to 160 μm (or 50 μm to 150 μm) in certain embodiments. “Soft-coated optical fibers” have a low hardness polymer coating (e.g., acrylic) typically with a nominal (i.e., stated) diameter no greater than twice the nominal diameter of the bare optical fiber. An outer diameter of a soft-coated optical fiber may be about 200 μm, about 250 μm, or another suitable value. In certain embodiments, an optical fiber having a glass core as disclosed herein may be configured to carry (e.g., conduct) optical signals in a wavelength range of 850 nm to 1550 nm. Optical fibers herein may encompass single-mode and multi-mode varieties.

“Concentricity” (or “concentricity error”) is defined as the distance between the geometric centers of two shapes/profiles, where one of the shapes surrounds the other shape. The shapes/profiles may be defined by different elements, such as the outer surface of a polymer coating and the outer surface of a core as discussed in greater detail below. Thus, the concentricity of a polymer coating relative to a core is the distance between a geometric center of the polymer coating and a geometric center of the core.

Reference will now be made in detail to the presently preferred embodiments, examples of which are illustrated in the following drawings. Whenever feasible, the same or corresponding reference numerals will be used throughout the drawings to refer to the same or like parts.

The embodiments set out below represent the information to enable those skilled in the art to practice the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

1 1 FIGS.A-C 1 FIG.A 10 12 14 12 10 20 14 12 14 12 12 14 12 12 14 14 14 14 are cross-sectional views of exemplary optical fibers that may be used in coherent fiber optic bundle breakout cable assemblies as disclosed herein, with such optical suitable for being arranged in direct lateral contact with one another in two-dimensional arrays of trunk fiber bundles or breakout bundles of such cable assemblies.is a cross-sectional view of an exemplary uncoated (bare) optical fiberA that includes a silica glass coreand silica glass claddingsurrounding the glass core, with the optical fiberA having an outer surfaceA defined by the glass cladding. The corehas a higher refractive index than the cladding. The corecomprises silica glass, which may be undoped silica glass, undoped silica glass, and/or downdoped silica glass. For a single-mode optical fiber, the radius of the coremay be in the range from about from about 3.0 μm to about 6.5 μm, or in the range from about 3.5 μm to about 6.0 μm, or in the range from about 4.0 μm to about 6.0 μm, or in the range from about 4.5 μm to about 5.5 μm. For a multi-mode fiber, the radius of the core may be in the range of about 4 μm to about 100 μm, or any suitable subrange thereof. The claddingis composed of one or more materials with an appropriate refractive index differential to provide desired optical characteristics with the core. In embodiments in which coreis doped with Ge and/or Cl, the claddingmay comprise silica that is substantially free of Ge and/or Cl. In some embodiments, the radius of claddingmay be in the range from about 8.0 μm to about 16.0 μm, or in the range from about 9.0 μm to about 15.0 μm, or in the range from about 10.0 μm to about 14.0 μm, or in the range from about 10.5 μm to about 13.5 μm, or in the range from about 11.0 μm to about 13.0 μm. The thickness of the claddingmay be in the range from about 3.0 μm to about 10.0 μm, or from about 4.0 μm to about 9.0 μm, or from about 5.0 μm to about 8.0 μm. Optionally, the claddingmay include a titanium-doped stress layer portion along an exterior thereof.

1 FIG.B 1 FIG.C 10 12 14 12 16 14 10 20 16 10 12 14 12 16 14 18 16 10 20 18 16 18 10 is a cross-sectional view of a hard coated optical fiberB including a silica glass core, silica glass claddingsurrounding the glass core, and a first hard coating layer(e.g., a hard or high-modulus coating) applied to an exterior of the cladding, with the optical fiberB having an outer surfaceB defined by the first hard coating layer.is a cross-sectional view of a hard coated optical fiberC including a silica glass core, silica glass claddingsurrounding the core, a first hard coating layer(e.g., a hard or high-modulus coating) applied to an exterior of the cladding, and a second coating layerapplied over the first hard coating layer, with the optical fiberC having an outer surfaceC defined by the second coating layer. In certain embodiments, the second coating layermay comprise a hard coating layer. In certain embodiments, the second coating layermay comprise a very thin colored or pigmented layer, that may or may not have a high modulus of elasticity, but may be sufficiently thin (e.g., preferably less than 3 μm, less than 2 μm, or less than 1 μm) to have negligible impact on compressibility (and therefore external hardness properties) of the optical fiberC.

16 18 40 10 10 46 12 2 2 In certain embodiments, a hard coating layer (and/or) may comprise a hard polymer coating material having a substantially consistent thickness (and therefore a substantially consistent outer diameter) along a length of optical fiber. In some embodiments, the thickness of a polymer coating is in a range of from 20 nm to 20 μm, or in a range of between 0.1 μm and 10 μm. In some embodiments, the thickness of a hard polymer coating is between 0.1 μm and 10 μm, 0.1 μm and 5 μm, or 0.1 μm and 2.5 μm about the circumference of an optical fiber (A-C). In some embodiments, the thickness of a hard polymer coating has a standard deviation ranging between 0.1 μm and 0.5 μm, 0.1 μm and 0.3 μm, or 0.1 μm and 0.2 μm. The hard polymer coatingis made of various materials including UV-cured acrylates or organic UV-curing acrylate resins filled with SiOor ZrOnanoparticles or non-acrylate polymers such as polyimides. A hard polymer coating may also include a silane additive to promote bonding to glass or inorganic surfaces. In some embodiments, the silane additive includes acryloxy silanes, methacrylate silanes, or Mercapto silanes, such as (3-Mercaptopropyl) trimethoxysilane and (3-acryloxypropyl) trimethoxysilane. In some embodiments, a hard polymer coating has an elastic modulus value greater than 0.3 GPa, greater than 1 GPa, or greater than 2.5 GPa. In one embodiment, a hard polymer coating has an elastic modulus higher than 0.5 GPa or higher than 1 GPa. In another embodiment, a hard polymer coating has an elastic modulus of about 2.5 GPa. In some embodiments, a hard polymer coating has a hardness (Shore D) value greater than 60, greater than 70, greater than 80, greater than 90, or greater than 100. In one embodiment, a hard polymer coating has a hardness (Shore D) value of about 95. In some embodiments, a hard polymer coating has a pencil hardness value greater than 3H, greater than 4H, or greater than 5H on Polymethylmethacrylate (PMMA) film. In some embodiments, a hard polymer coating has a thickness between 0.1 μm and 10 μm, a Shore D hardness greater than 60, and a concentricity relative to a fiber core () ranging between 0.1 μm and 0.5 μm.

16 18 10 10 12 16 18 12 16 18 12 In certain embodiments, a hard polymer coating (e.g.,and/or) may be applied onto a glass optical fiber (A-C) such that a concentricity of the hard polymer coating relative to the coreis limited to a narrow range. In some embodiments, the concentricity of a hard polymer coating (and/or) relative to the coreranges between 0.1 μm and 0.5 μm, 0.1 μm and 0.3 μm, or 0.1 μm and 0.2 μm. In one embodiment, the concentricity of a polymer coating (and/or) relative to a coreis less than about 0.15 μm. Additional details concerning formation of hard polymer coatings on glass optical fibers are disclosed in U.S. Patent Application Publication No. 2022/0026604 A1 published on Jan. 27, 2022 in the name of Corning Research & Development Corporation, wherein the entire contents of the foregoing publication are hereby incorporated by reference herein.

2 FIG.A 30 30 32 36 36 32 34 32 36 36 35 34 49 32 36 36 49 36 36 32 40 42 36 36 50 50 52 52 is a perspective view of an exemplary coherent fiber optic bundle breakout cable assemblyaccording to one embodiment. The cable assemblyincludes a trunk fiber bundleand multiple breakout bundlesA-M emanating from the trunk fiber bundle. A furcation sectionis provided at a transition between the trunk fiber bundleand the breakout bundlesA-M, with adhesive materialbeing arranged (e.g., potted) at the furcation sectionto protect fibers at the transition. Optionally, cable jacket materialand/or a furcation tube may be arranged over the trunk fiber bundleand/or over each breakout bundleA-M for environmental protection and wear resistance. Optionally, cable jacket materialmay be embodied in a furcation tube. Although thirteen breakout bundlesA-M of identical lengths are shown, it is to be appreciated that any suitable number of breakout bundles may be provided, and that breakout bundles may have differing lengths if desired. As shown, the trunk fiber bundleincludes a trunk fiber connectorhaving a trunk fiber connector end, and each breakout bundleA-M includes a breakout bundle connectorA-M having a corresponding breakout bundle connector endA-M. In certain embodiments, multiple breakout bundles may be received by a multi-bundle connector configured to receive two or more breakout bundles.

2 FIG.B 52 36 30 36 50 51 54 36 37 37 52 51 37 52 shows a single breakout connector endA of one breakout bundleA of the cable assembly, with the breakout bundleA including a breakout connectorA having a breakout bundle ferruleA having a breakout bundle ferrule apertureA receiving optical fibers of the breakout bundleA, with optical fiber endsA being shown. In certain embodiments, the optical fiber diced endsA may be substantially flush with the breakout bundle connector endA that is defined by the breakout bundle ferruleA. As shown, the optical fiber endsA are in lateral contact with one another at the breakout connector endA in a close-packed two-dimensional array (encompassing nineteen optical fibers) having a hexagonal shape.

2 FIG.C 42 32 30 32 40 41 44 33 32 33 42 51 33 42 shows a trunk connector endof trunk fiber bundleof the cable assembly, with the trunk fiber bundleincluding a breakout connectorincluding a trunk fiber ferrulehaving a trunk fiber ferrule aperturereceiving a plurality of optical fibers, with optical fiber endsof the trunk fiber bundlebeing shown. In certain embodiments, the optical fiber endsmay be substantially flush with the trunk connector endthat is defined by the trunk fiber ferruleA. As shown, the optical fiber endsare in lateral contact with one another at the trunk connector endin a close-packed two-dimensional array (encompassing three hundred, thirty-one optical fibers) having a hexagonal shape.

36 36 32 30 33 32 66 66 10 66 66 10 32 66 66 36 36 66 66 10 32 61 61 10 10 61 61 36 36 42 52 52 61 61 10 32 66 66 10 42 36 36 36 36 52 52 66 66 33 42 10 36 36 32 10 2 FIG.A 3 FIG.A 2 FIG.A 2 FIG.A 2 FIG.A 2 FIG.A 2 FIG.A As noted above, the breakout bundlesA-M emanate from the trunk fiber bundleof the coherent fiber optic bundle breakout cable assemblyof.shows optical fiber endsof the trunk fiber bundle, with superimposed identification of thirteen hexagonal groupsA-M of contiguously arranged optical fibers, wherein each groupA-M contains nineteen optical fibersrepresenting a subset of the plurality of optical fibers of the trunk fiber bundle, and each groupA-M corresponds to a different fiber optic breakout bundle of the fiber optic breakout bundlesA-M shown in. Outside the groupsA-M of optical fibers, the trunk fiber bundlefurther includes six groupsA-F of non-functional fibers′ (with fourteen non-functional fibers′ per groupA-F) that are not included in the breakout bundlesA-M of, and therefore are not capable of transmitting optical signals between the trunk connector endand the breakout connector endsA-M. The six groupsA-F of non-functional fibers′ are distributed around six sides of the hexagonal array of optical fibers of the trunk fiber bundle. With a known orientation and placement of the hexagonal groupsA-M of optical fibersat the trunk connector endcorresponding to the fiber optic breakout bundlesA-M (shown in), optical fibers of the breakout bundlesA-M at the breakout connector end facesA-M (in) are mapped to optical fibers of corresponding groupsA-M of optical fiber endsat the trunk connector end face(in). Thus, a one-to-one correspondence may be established between individual optical fibersof the breakout bundlesA-M and optical fibers of the trunk fiber bundlewithout need for marking of each individual optical fiber.

3 FIG.B 3 FIG.A 3 FIG.B 33 32 66 66 68 61 61 10 66 66 10 66 66 66 66 In certain embodiments, one or more optical fibers (preferably at least one peripheral optical fiber) of the plurality of optical fibers of the trunk fiber bundle may be marked (e.g., with an exteriorly arranged ink, pigment, coating, surface treatment, or the like, or interiorly arranged colored or contrasting doping) to provide polarity identification.shows the optical fiber endsof the trunk fiber bundleand superimposed hexagonal groupsA-M previously shown in, with a single marker fiberat a perimeter of the hexagonal array being part of the one of the groupsA-F of non-functional fibers′.also includes sequential identifiers A to M for the superimposed hexagonal groupsA-M of optical fibersthat correspond to breakout bundles. As shown, the identifiers for the hexagonal groupsA-M are sequential incremented by vertical position, with the uppermost group having identifier “A” corresponding to groupA, and the lowermost group having identifier “M” corresponding to groupM.

4 FIG. 36 10 1 10 18 19 10 1 10 18 19 10 1 10 18 20 1 20 18 19 37 36 10 1 10 18 19 37 36 In certain embodiments, fiber optic breakout bundles may include one or more marker fibers to provide polarity identification. The marker fiber may be functional.is a perspective view of a portion of a fiber optic breakout bundleA having a total nineteen optical fibers in a close-packed hexagonal array, including eighteen unmarked optical fibers-to-, and one peripheral marker fiberembodying an optical fiber that is marked (e.g., along an exterior or interior thereof) to serve as a marker fiber for polarity identification, to provide a total of nineteen functional optical fibers-to-,. As shown, the unmarked optical fibers-to-include external surfaces-to-that are in lateral contact with one another (and with the marker fiber) at optical fiber endsA of the breakout bundleA. As will be described hereinafter in conjunction with a method for fabricating a coherent fiber optic bundle breakout cable assembly, interstitial spaces between the optical fibers-to-and the marker fiberproximate to the optical fiber endsA may include bonding material to preserve the placement of optical fibers of the breakout bundleA.

10 10 44 41 10 10 44 70 3 3 FIGS.A,B 2 FIG.C 2 FIG.C 3 3 FIGS.A,B 2 FIG.C 5 FIG. As noted hereinabove, an exemplary method for fabricating a coherent fiber optic bundle breakout cable assembly includes multiple steps. One step includes terminating a plurality of optical fibers (e.g.,,′ in) in a close-packed two-dimensional array configuration within a trunk fiber ferrule aperture (e.g.,in) of a trunk fiber ferrule (e.g.,in) arranged at a first end portion of the plurality of optical fibers, wherein each optical fiber (e.g.,,′ in) of the plurality of optical fibers within the trunk fiber ferrule aperture (in) is arranged in lateral contact with multiple other optical fibers of the plurality of optical fibers. Another step includes holding a second length portion of the plurality of optical fibers with an elastomeric fixture (e.g., fixtureshown in), wherein each optical fiber of the plurality of optical fibers is arranged in lateral contact with multiple other optical fibers of the plurality of optical fibers within the elastomeric fixture. Another step includes dicing the plurality of optical fibers proximate to the elastomeric fixture to provide diced ends of optical fibers of the plurality of optical fibers. Another step includes selectively applying bonding material in interstitial spaces between optical fibers of the plurality of optical fibers proximate to the diced ends according to a bundle-forming pattern. Another step includes curing the bonding material selectively applied to the interstitial spaces. Another step includes separating groups of optical fibers of the plurality of optical fibers into a plurality of breakout bundles, wherein each breakout bundle includes a single bundle or a pair of sub-bundles of bonded optical fibers arranged in a close-packed two-dimensional array configuration and generated by curing the bonding material selectively applied to the interstitial spaces. Yet another step includes, for each breakout bundle of the plurality of breakout bundles, retaining the breakout bundle in a corresponding breakout bundle ferrule aperture of one or more breakout bundle ferrules.

5 FIG. 5 FIG. 70 71 72 70 74 71 72 32 74 70 32 32 70 32 32 is a perspective view of an elastomeric fixturehaving opposed first and second faces,, the elastomeric fixturedefining a hexagonal apertureextending between the first and second faces,.additionally shows a length portion of a trunk fiber bundle(intermediate between bundle ends, and including a plurality of optical fibers in a close-packed hexagonal array) extending through the hexagonal aperture. The elastomeric fixtureis intended to gently compress optical fibers of the trunk fiber bundleto retain direct lateral contact therebetween, while being slidable relative to the trunk fiber bundle. With the elastomeric fixtureslidably retaining optical fibers of the trunk fiber bundlein a close-packed configuration, optical fibers of the trunk fiber bundlemay be diced.

32 32 32 32 32 In certain embodiments, dicing may be performed by laser dicing (also known as laser cleaving), such as ultrafast laser nano-perforation or non-dicing using a Bessel beam, preferably while a portion of the trunk fiber bundleis immersed in an index matching liquid (i.e., a liquid index matched to the optical fibers of the trunk fiber bundle) such as water. A laser beam is only slightly refracted through the trunk fiber bundlewhen it is immersed in an index matching liquid. Immersion in index matching liquid is beneficial to avoid laser beam refraction that would result in a dry condition, whereby interstitial air interfaces in the trunk fiber bundle would strongly refract the laser beam and thereby laser penetrating depth to less than two layers of fibers. If Bessel beam dicing is used with the trunk fiber bundleimmersed in an index matching liquid, the collimation length of the Bessel beam may be designed to at least match the total thickness of the trunk fiber bundle. In certain embodiments, collimation length of a Bessel beam may exceed 3 mm, which is sufficient to cover a wide range of sizes of trunk fiber bundle sizes. Laser processing results in a flat end face of optical fibers of the trunk fiber bundle. In contrast, mechanical cutting or lapping of a loosely held trunk fiber bundle would be anticipated to result in fiber length variations of over 1 mm, which may render difficult any subsequent selective application of bonding material in interstitial spaces between diced optical fibers of the trunk fiber bundle.

6 FIG. 5 FIG. 32 70 75 32 32 76 75 78 32 76 32 32 32 37 32 32 75 76 is a side elevational view of the trunk fiber bundleand elastomeric fixtureofin conjunction with an open container, with a portionA of the trunk fiber bundlebeing immersed in an index-matching liquidwithin the container, and with a laser beambeing impinged on the portion of the immersed trunk fiber bundleA for dicing optical fibers thereof. As noted above, the laser dicing may include Bessel beam dicing, and the index-matching liquidmay include water. Upon completion of laser dicing, an end portion′ is separated from the remainder of the trunk fiber bundle, and the trunk fiber bundleincludes diced endsof optical fibers of the trunk fiber bundle. The trunk fiber bundlemay be removed from the containerand index matching liquidafter laser dicing is complete.

32 37 70 37 32 32 74 72 70 37 32 37 32 32 37 32 7 FIG. Following dicing of the trunk fiber bundleto form diced ends, bonding material is selectively applied in interstitial areas between optical fibers proximate to the diced ends according to a bundle forming pattern configured to produce multiple breakout bundles (optionally including sub-bundles that may be subsequently paired to form breakout bundles). As shown in, in certain embodiments, the elastomeric fixturemay be positioned (e.g., by sliding) to cause diced endsof the trunk fiber bundle(of the trunk fiber bundlestill retained within the fixture aperture) to be proximate to, or substantially flush with, one face (e.g., face) of the elastomeric fixture, prior to application of bonding material. One example of a suitable bonding material that may be applied to interstitial spaces between diced endsof a trunk fiber bundleis an ultraviolet (UV) curable adhesive material. Other bonding materials may be used, such as thermally curable adhesives, chemically curable adhesives, epoxies, or the like. After deposition of bonding material, such material may be cured by a method appropriate to the bonding material (e.g., via UV emissions, heat, chemical addition, etc.). In certain embodiments, bonding material may be selectively applied to interstitial spaces between diced endsof a trunk fiber bundlevia deposition by piezoelectric jetted (e.g., inkjet-style) printing, followed by curing. In certain embodiments, a mask defining multiple openings (e.g., windows corresponding to a bundle-forming pattern) may be applied over diced ends of a trunk fiber bundle, and bonding material may be selectively applied to interstitial spaces between diced endsof the trunk fiber bundleby application of bonding material openings of the mask, followed by curing of the bonding material. If the bonding material comprises UV-curable adhesive, a suitable mask may be hydrophobic and UV-impermeable, and the mask may remain present during a UV curing step. If UV-curable bonding should wick (or otherwise leak) to areas between (and not overlapped by) windows in the mask, presence of a UV-impermeable mask may beneficially prevent curing of the bonding material in areas of the bundle not overlapped by windows in the mask.

8 FIG.A 6 7 FIGS.and 80 82 86 86 80 37 32 80 86 86 80 80 is top plan view of a maskincluding a bodydefining thirteen hexagonal-shaped openingsA-M, with the maskbeing configured to overlay diced endsof optical fibers of the trunk fiber bundleof. In certain embodiments, the maskcomprises a hydrophobic and UV-impermeable material. The openingsA-M in the maskmay be defined by laser cutting, waterjet cutting, blade cutting, or the like. In certain embodiments, one surface of the maskconfigured to contact diced ends of optical fibers may comprise non-permanent adhesive to promote sealing.

8 FIG.B 8 FIG.A 7 FIG. 8 FIG.C 8 FIG.B 8 FIG.B 8 FIG.D 8 FIG.C 8 8 FIGS.A-C 2 FIG.A 80 37 86 86 80 29 37 37 37 80 37 89 86 86 80 29 37 36 36 36 36 89 89 86 86 80 37 86 86 86 86 80 89 86 86 36 36 20 is a top plan view of the maskofsuperimposed over diced endsof optical fibers of the trunk fiber bundle of. Each openingA,M in the maskexposes interstitial spacesbetween diced endsof nineteen contiguous optical fibers (exposing diced endsof seven optical fibers in their entirety, and diced endsof portions of twelve additional optical fibers) arranged in a hexagonal configuration. In certain embodiments, the maskmay be removably adhered to diced endsof underlying optical fibers.shows the items offollowing application of bonding materialthrough the openingsA-M in the maskto be received in interstitial spaces (in) between diced endsof optical fibers according to a bundle-forming pattern configured to form thirteen groupsA-M of optical fibers, with each groupA-M having nineteen bonded optical fibers. After application of bonding material, the bonding materialis cured (e.g., by impinging UV emissions through the openingsA-M in the mask, or by other curing means as disclosed herein).shows the diced endsof optical fibers of the trunk fiber bundle offollowing removal of the mask, with superimposed dashed line hexagons embodying bonding material application areasA′-M′ corresponding to the openingsA-M in the maskof. As shown, bonding materialis provided within the bonding material application areasA′-M′ and is subsequently cured to form thirteen groups of bonded optical fibersA-M that will correspond to breakout bundles of a cable assembly (e.g., coherent fiber optic bundle breakout cable assemblyin).

8 FIG.E 8 FIG.E 3 FIG.A 2 FIG.A 8 FIG.A 2 FIG. 2 FIG. 4 FIG. 36 36 10 89 37 10 61 61 10 36 36 34 36 36 36 36 80 49 36 36 32 49 36 36 36 36 36 36 19 36 36 36 36 is an end view of the thirteen breakout bundlesA-M of optical fibersseparated from one another and formed by the selective application of bonding materialin interstitial areas of the diced endsof the optical fibers. In, unbonded fibers (corresponding to the six groupsA-F of non-functional fibers′ shown in) are omitted, since any unbonded fibers are not included in the breakout bundlesA-M, and may be trimmed to a furcation section (e.g., furcation sectionshown in). To aid in separating the breakout bundlesA-M from one another, each breakout bundleA-M may be passed through a corresponding tight-clearance hexagonal opening in a separation fixture (which may be substantially identical in appearance to the maskshown in). Cable jacket material (in) may be placed over each breakout bundleA-M and over the trunk fiber cable (in). If desired, the cable jacket materialof each breakout bundleA-M cable jacket may comprise different colors, number, and/or other markings specific to each breakout bundleA-M. In certain embodiments, each breakout bundleA-M may include a marker fiber (e.g.,as shown in) for polarity identification. In certain embodiments, after the breakout bundlesA-B are separated from one another, each breakout bundleA-B may be retained in an aperture of a single-aperture breakout bundle ferrule or a multi-aperture breakout bundle ferrule.

9 FIG. 2 FIG. 8 FIG.E 30 35 34 39 32 36 36 29 In certain embodiments, after breakout bundles are separated from one another (e.g., and after non-functional fibers are trimmed to a furcation section), adhesive material may be applied to a furcation section representing a transition between a trunk fiber bundle and the multiple breakout bundles, to provide environmental and mechanical protection.is a perspective view of a portion of a coherent fiber optic bundle breakout cable assembly (e.g., corresponding to the assemblyshown in), showing the presence of adhesive materialbinding optical fibers at a furcation sectionincluding a transition pointbetween a trunk fiber bundleand the plurality of breakout bundlesA-B each including bonding material (in) in interstitial areas along diced fiber ends thereof.

10 FIG. In order to improve fiber utilization when forming breakout bundles from a trunk fiber bundle, in certain embodiments, selected fibers of a trunk fiber bundle may be arranged into sub-groups of optical fibers having adhered diced ends, wherein pairs of subgroups may be combined (without twist) to form additional trunk fiber bundles. One example of such an embodiment will be described in connection with.

10 FIG. 10 FIG. 133 10 10 132 10 166 166 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 166 1 166 2 10 132 10 is a top plan view of diced endsof optical fibers (including functional fibersand non-functional fibers′) of a trunk fiber bundlearranged in a close-packed hexagonal array, following selective application of adhesive material in interstitial areas between functional optical fibersto form thirteen hexagonal groupsA-M of bonded optical fibers and six trapezoidal subgroupsN-,N-,O-,O-,P-,P-of bonded optical fibers, suitable for forming sixteen hexagonal breakout bundles of a coherent fiber optic bundle breakout cable assembly according to one embodiment. The six trapezoidal subgroups includes three pairs of trapezoidal subgroupsN-,N-,O-,O-,P-,P-of bonded optical fibers, wherein one pair of subgroupsN-,N-may be combined to form one hexagonal group, another pair of subgroupsO-,O-may be combined to form another hexagonal group, and another pair of subgroupsN,N-may be combined to form yet another hexagonal group. This arrangement reduces the number of non-functional fibers′ omitted from a coherent fiber optic bundle breakout cable assembly, and therefore improves fiber utilization and bandwidth capability. In the embodiment shown in, sixteen hexagonal groups each including nineteen functional optical fibers may be functional fibers, permitting three hundred four (304) optical fibers to be utilized of a total of three hundred thirty-one (331) optical fibers of the trunk fiber bundle(for a utilization rate of 91.8%), such that only twenty-seven of the three hundred four total optical fibers (i.e., are non-functional fibers′ (for a non-utilization rate of 8.2%). In certain embodiments, a coherent fiber optic bundle breakout cable assembly has at least 60, at least 100, at least 200, at least 300, at least 400, at least 600, at least 800, at least 1200, at least 1600, or at least 2000 total fibers, with a functional fiber utilization rate of at least 80%, at least 85%, at least 90%, or at least 92%.

51 50 50 41 32 70 2 FIG.B 2 FIG.A 2 FIG.C 2 2 FIGS.A,C 5 7 FIGS.- After formation of breakout bundles, breakout bundle ferrules (e.g.,A in) may be affixed over bundled optical fibers to form breakout fiber connectors (e.g.,A-M in). A trunk fiber ferrule (e.g.,in) may be arranged over an opposing end of a trunk fiber bundle (e.g.,in) prior to utilization of an elastomeric fixture (in) employed during optical fiber dicing and breakout bundle formation.

11 FIG. Although various figures of the present application depict a trunk fiber bundle and breakout bundles each having optical fibers arranged in a close-packed two-dimensional array having a hexagonal shape, the disclosure is not limited to use of hexagonal cross-sectional shapes for trunk fiber bundles and breakout bundles. Any suitable cross-sectional shapes may be employed for producing trunk fiber bundles and/or breakout bundles, including rectangular, triangular, trapezoidal, and other shapes, wherein it is noted that a trunk fiber bundle may have a different geometric shape than corresponding breakout bundles. Additionally, differing breakout bundles emanating from the same trunk fiber bundle may include different numbers of optical fibers in certain embodiments. of One example of a trunk fiber bundle being used to form multiple generally rectangular breakout bundles is shown in.

11 FIG. 232 266 266 266 266 10 232 10 is a top plan view of diced ends of optical fibers of a trunk fiber bundlehaving a rectangular configuration suitable for forming twelve rectangular breakout bundlesA-L of a coherent fiber optic bundle breakout cable assembly according to one embodiment. Each breakout bundleA-L includes seventeen (17) functional fibers, with the trunk fiber bundleincluding various non-functional fibers′ (totaling thirty-four in number) along selected areas of a perimeter thereof, providing a functional fiber utilization rate of 85.7%.

Coherent fiber optic bundle breakout cable assemblies as disclosed herein may be applied to various end uses, including but not limited to optical switching for GPU clusters for generative AI applications, parallel computing, and the like.

12 FIG. 9 FIG. 2 FIG. 300 30 1 30 30 1 30 39 32 30 1 30 36 36 30 1 30 n n n n is a schematic illustration of an optical switching arrangementincluding multiple graphic processing units GPU1-GPUn and multiple switches SW1-SWm being interconnected with multiple coherent fiber optic bundle breakout cable assemblies-to-as disclosed herein. A total of n GPUs (i.e., GPU1-GPUn) are connected by a total of m switches SW1-SWm in a Clos network to form a GPU scale-up system in a similar design as the Nvidia GB200 NVL system (Nvidia Corporation, Santa Clara, California). The GPUs (GPU1-GPUn) and switches (SW1-SWm) can be located in the same rack or different racks. The coherent fiber optic bundle breakout cable assemblies-to-allow any of the GPUs (GPU1-GPUn) to connect to multiple switches (SW1-SWm). In a multi-rack system, the furcation point (e.g.,in) of a trunk fiber bundle (e.g.,in) of each coherent fiber optic bundle breakout cable assembly-to-can land on a switch rack containing the switches (SW1-SWm), and relatively short breakout bundle legs (e.g.,A-M) are needed to reach the switches (SW1-SWm). The lengths of the breakout bundle legs can be staggered according to the designed positions of the switches (SW1-SWm). A coherent fiber optic bundle breakout cable assembly may replace a large number of smaller cables as compared to use of point-to-point connections, thereby greatly reducing cable congestion. More importantly, use of the coherent fiber optic bundle breakout cable assemblies-to-offers much higher bandwidth density than point-to-point connections, with such bandwidth density being critical crucial for in-package integration of optics with GPU chips.

In certain embodiments, a coherent fiber optic bundle breakout cable assembly may be arranged within a switch box, wherein short internal breakout bundles may be used to increase bandwidth density at a trunk bundle end for in-package optics on a switch chip, with internal breakout bundles being couplable to breakout inputs at connectors located along a switch box front panel.

302 302 50 1 50 36 1 36 13 FIG. 12 FIG. An exemplary switch boxA including one switch unit SW is shown in. In certain embodiments, the switch boxA includes connector ports-A to-nA configured to receive connector ends of breakout bundles-A to-nA (each corresponding to a different coherent fiber optic bundle breakout cable assembly) from multiple different GPUs (e.g., GPU1-GPUn in).

14 FIG. 40 1 40 4 32 1 32 4 is a schematic illustration of a graphic processing unit (GPU) assembly including multiple GPUs (GPU1 to GPU4) with in-package optics, receiving trunk bundle connectors-to-of multiple coherent fiber optic bundle breakout cable assemblies-to-as disclosed herein.

In certain embodiments, a trunk fiber bundle of a first coherent fiber optic bundle breakout cable assembly connects to a transmitter array of in-package optics of a GPU or GPU assembly, and a trunk fiber bundle of a second first coherent fiber optic bundle breakout cable connects to a receiver array of in-package optics of the GPU or GPU assembly. In another embodiment, part of a trunk bundle of a coherent fiber optic bundle breakout cable connects to a transmitter array for a GPU or GPU assembly, another part of the trunk bundle of the same first coherent fiber optic bundle breakout cable connects to a receiver array of the same GPU or GPU assembly.

12 14 FIGS.- Each linear link shown inimplies a logic link that may include multiple trunks or bundles, depending on bandwidth requirements. For example, if sixteen optical fibers of one breakout bundle, each carrying 25 Gb/s, are used to transmit a total breakout bandwidth of 400 Gb/s, a trunk fiber bundle incorporating the sixteen breakout bundles may support 6.4 Tb/s. If a single GPU has an I/O bandwidth of 12.8 Tb/s, then in-package optics may require two trunk bundles for transmitters, and two bundles for receivers. The total number of switches in such an instance may be 32, matching the breakouts of two cable assemblies. The I/O bandwidth for one or more GPUS can scale by increasing the number of trunk bundles and/or reducing the fiber diameter. A transmitter array pattern and receiver array pattern can be designed accordingly based on the specific coherent fiber optic bundle breakout cable assembly.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention.

It will also be apparent to those skilled in the art that unless otherwise expressly stated, it is in no way intended that any method in this disclosure be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim below does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.